1. Technical Field
This disclosure relates to a wheel hub for a motor vehicle such as a tractor-trailer. More specifically, this disclosure relates to a wheel hub having a design reducing stress concentrations at a barrel and flange.
2. Description of the Related Art
Wheel hubs connect the wheel of a vehicle to the axle and, therefore, are subjected to significant loads in bearing the weight of the vehicle. Furthermore, wheel hubs contribute to a portion of the overall weight of vehicles designed for commercial freight hauling and similar uses. Such commercial vehicles are subject to state and federal regulations that impose restrictions on the overall weight of the loaded vehicle. Thus, any reduction in the weight of the wheel hubs will directly increase the amount of freight that can be hauled by such vehicles. However, the weight of a wheel hub cannot easily be reduced because the wheel hub must be strong enough to withstand stresses generated during use.
FIG. 1 illustrates a perspective view of the outboard side of a conventional wheel hub. FIG. 2 illustrates a section view of the wheel hub shown in FIG. 1, as viewed along line II-II′ shown in FIG. 1.
Referring to FIGS. 1 and 2, a conventional wheel hub 10 generally includes a barrel 12 and a flange 14 connected to the barrel 12 by a connection member 16. A vehicle's wheel (not shown) is secured to the flange 14 by bolts (not shown) extending through apertures 14a formed in the flange 14. Pilot bosses 18 are used to align the wheel and brake drum to the wheel hub 10. The vehicle's axle (not shown) is received by a hub cavity 20 within the barrel 12. The axle is supported within the hub cavity 20 by an inboard bearing assembly and an outboard bearing assembly (both not shown), which are respectively disposed within an inboard bearing bore 22 and an outboard bearing bore 24 formed within the barrel 12 at opposite ends of the hub cavity 20.
In addition, a conventional wheel hub 10 often includes ribs 26 to provide added mechanical support to the pilot bosses 18. Each rib 26 typically extends from the connection member 16 and connects a pilot boss 18 directly to the barrel 12.
During operation of a vehicle, the axle is subjected to forces which tend to bend the barrel 12 relative to the flange 14. As shown in FIG. 2, each rib 26 connects a pilot boss 18 to a portion of the barrel 12 surrounding the hub cavity 20. Thus, load paths extending between the barrel 12 and the flange 14 travel through each pilot boss 18. As a result, the ribs 26 tend to generate regions of concentrated stress within the barrel 12 and the flange 14 when the barrel 12 bends relative to the flange 14. Cracks can be undesirably generated in the barrel 12 and the flange 14 due to the regions of concentrated stress.